Ink jet printers eject ink onto a print medium such as paper in controlled patterns of closely spaced dots. To form color images, multiple ink jet printheads are used, with each head being supplied with ink of a different color from an associated ink container. The printing system may be incorporated in either a carriage type printer or a pagewidth type printer. A carriage type printer, such as the type disclosed, for example, in U.S. Pat. Nos. 4,571,599 and Re. 32,572, generally include a relatively small printhead containing ink channels and nozzles. The contents of these patents are hereby incorporated by reference. The printhead is usually sealingly attached to an ink supply container and the combined printhead and container form a cartridge assembly which is reciprocated to print one swath of information at a time on a stationarily held recording medium, such as paper. After the swath is printed, the paper is stepped a distance equal to the height of the printed swath, so that the next printed swath will be contiguous therewith. The procedure is repeated until the entire page is printed. The pagewidth printer has a stationary printhead having a length equal to or greater than the width of the paper. The paper is continually moved past the pagewidth printhead in a direction normal to the printhead length at a constant speed during the printing process. An example of a pagewidth printer is found in U.S. Pat. No. 5,221,397, whose contents are hereby incorporated by reference.
A known problem with thermal ink jet printers is the degradation in the output print quality due to a change in the volume of ink ejected at the printhead nozzles resulting from fluctuations of printhead temperatures. These temperatures produce variations in the size of the ejected drops which result in the degraded print quality. The size of ejected drops varies with printhead temperature because two properties that control the size of the drops vary with printhead temperature: the viscosity of the ink and the amount of ink vaporized by a firing resistor when driven with a printing pulse. Printhead temperature fluctuations commonly occur at printer startup, during changes in ambient temperature, and when the printer output varies.
When printing text, gray scale images, and/or color images the darkness, contrast and color rendition may vary with printhead temperature. To print text, graphics, or images of the highest quality, the printhead temperature must remain constant. In addition, not only must the printhead temperature remain constant, each of the printheads, either within a single printing machine or among a variety of machines must print consistently from printhead to printhead so that the printed output of such machines remains consistent. Consequently, the calibration of the temperature sensors among the various printheads must be performed.
Various printhead temperature controlling systems and methods are known in the prior art for sensing printhead temperature and using sensed temperature signals to compensate for temperature fluctuations or increases. Likewise, fuse programmable circuits and fusible links are also known.
In U.S. Pat. No. 4,551,685 to Kerns, Jr. et al., a programmable gain feedback amplifier is described. A decoding and programming circuit for receiving an input programming command signal is used to selectively blow, or open, the proper fuses to establish a desired signal attenuation in a described network. After programming, the gain of the amplifier circuit, which is related to the total attenuation of the network, is permanently set, and does not require the programming signal to be continuously applied.
U.S. Pat. No. 4,879,587 to Jerman et al., describes a fusible link. The fusible link comprises a semi-conductor substrate, an electrically insulating layer on the substrate, a pair of conductor elements on the surface of the insulating layer opposite the substrate, and a fuse conductor layer on the surface of the insulating layer opposite the substrate electrically connecting the conductor elements.
U.S. Pat. No. 5,025,300 to Billig et al., describes an integrated circuit including a conductive fusible link that may be blown by laser energy. A dielectric material covering the fuse is etched away to expose the fuse.
U.S. Pat. 5,075,690 to Kneezel discloses an analog temperature sensor for an ink jet printhead which achieves a more accurate response by forming the thermistor on the printhead substrate and of the same polysilicon material as the resistors which are heated to expel droplets from the printhead nozzles.
U.S. Pat. No. 5,387,823 to Ashizawa describes a fuse-programmable control circuit including a master control circuit with a first fusible link that controls the feeding of power to a fuse-programmable memory. If output of signals from the fuse-programmable memory is not required, the first fusible link is cut. If output of signals from the fuse-programmable memory is required, the first fusible link is left uncut and the fuse-programmable memory is programmed by cutting one fusible link in each of a number of pairs of fusible links.
U.S. Pat. No. 5,388,134 to Douglass et al describes an integrated circuit temperature detector using a temperature dependent oscillator to count up to a fixed number and thereby generate a time interval indicative of the temperature(a temperature to time interval converter).
U.S. Pat. No. 5,467,113 to Ishinaga et al. describes an ink jet recording head for discharging ink including heaters for warming a board and sensors for detecting the temperature of the board.